Manufacture of hyposulphites



De'c. 11,1923. 1 1,477,130

l H. KUHNE ETAL. l f,

MANUFACTURE 01"'` HYPOSULPHITES F11edVNQv. 18. 1921 Patented Dec.. 11, i923.

HANS KHNE, 0F LEVERKUSEN, AND FRANZ BENCKER, OF MULHEIM, G-

LOGNE, GERMANY, ASSIGNORS TO FARBENFABRIKEN VORM. FRIEDR, BAY

AND CO., OF LEVERKUSEN, NEAR COLOGNE, GERMANY.

MANUFACTURE OF HYPOSULPHITES.

. Application led November 18, 1921.

To all wko/m, t may conce-ra Be it known that We, HANS KHNE and FRANZ BENCKER, citizens of Germany, residing at, respectively, Leverkusen and Mulheim, near Cologne, Prussia, Germany, have invented new and useful Improvements in the Manufacture of Hyposulphites, of which the following is a specification.

lt is known that hyposulphites can be oi)- tained by causing sodium amalgam to react with an aqueous solution ot a bisullite (acid sultite).

This method however is not economical as a small yield only is obtained.

According to this invention highly concent1-ated hyposulphite (salts of the hyposulfurous acid H2S2O4) are obtained by treating a solution of a bisultite (NaHSO3, etc.) with an amalgam preferably that of an alkali metal and with a free acid llCl, H2SO4, SO2 for example. The best results are obtained it the acid is present in such quantity as is equivalent to the n'on-mercuria-l metal ot' the amalgam.

In carrying out the, invention the bisultite solution is well cooled and stirred, the amalgam and acid being added in proportionate quantities either in hatches or continuously.

Preferably the amalgam is obtained electrolytically, the mercury subseiluently set free b v the reaction being returned to the electrolytic cell.

The accompanying drawing' illustrates one form of apparatus suitable for carving out the invent-ion.

EampZe.-A caustic soda or sodium chlorid solution is electrolyzed in an electrolytic cell A, provided with an anode B of nickel and a cathode C of mercury. The sodium amalgam thus produced is then removed rom the cell through a Siphon D and run into a closed vessel E containing bisultite solution (NaHSO). The mixture is cooled and well stirred with the amalgam by the operation of the a itator K, care being taken to exclude air. he mercury set free is run from the vessel E through a siphon F to a pump G. which delivers it back to the electrolytic cell A. A free acid, HESOS for example is added simultaneously with the Serial No. 516,139.

amalgam to the bisulfite through the pipe L in a quantity in proportion to the current in the cell. The solution of hyposuiphitc thus obtained is then treated in the known manner. t'

The acid employed must of course he which is of such a nature that it n 1 destroy the hyposulphite product under the operating conditions. For example, the acid must be one which will not oxidize the hyposulphite product. In some of the apperl claims the expression non oxidizing@r is employed for the purpose ot exch i the use of such acids.

This indirect velectrolytic process has a Great advantage over the hitherto known direct electrolytic process in that Firstly troublesome diaphragms are avoidedj secondly the apparatus required is more simple as the electrolytic apparatus need not 'Zi be air tight and thirdly secondary reactions are avoided and also the reduction is more easily prevented from proceeding too tar. Having now particularly described and ascertainedthe nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:-

l. A process for the manufacture of hyposulphites which consists in treating a solution of a bisnliite with an amalgam and a free non-oxidizing, acid, substantially as described.

2. A process for the manufacture of hyposulphites which consists in treating a solution of a bisultite with an amalgam and a free 'non-oxidizing acid in quantity chemically equivalent to the non-mercurial metal of the amalgam.

3. Process for the manufacture o' hyposul hites as defined in claim l in which 9 03 is the free acid employed.

4. Process for the manufacture of hypo- Vsulphites as defined in claim 2 in which Hb()3 is the free acid emplo ed.

5. A cyclical process for t e manufacture of hyposulphites which consists in forming an amalgam electrolytically leading,` the amalgam into a solution ot a bisultite. cansing the reaction between the amalgam and the bisulte to take place in the presence oli a free non-oxidizing acid and returning the set our hands in the presence of two suhscrih mercury set free into the electrolytc cell. ing witnesses.

6. A cyclical process for the manufacture HANS KHNE. [ha] of hyposulplutes as defined 1n chum 5 1n Y I 5 which HQSO3 is the free acid employed in FRANZ BENCRER |11" S'] quantity equivalent to the non-mercurial ele- Witnesses:

ment of the amalgam.

ALFRED GUENTHER, In testxmony whereof We have hereunto ALFRED THAUss. Y 

